Try this if you see YouTube ads despite ad blocker installed in Chrome browser. A bug in Chrome 45+ versions causing YouTube ads to sneak through Ad blocking extensions –like Ublock Origin, Adblock Plus and other –and displayed to users.
At present, you can able to fix this by removing the YouTube app from Chrome browser, here is how you can do that.
Fix YouTube Ads not blocked in Chrome
1. Visit Chrome://apps page
2. Right click on YouTube app and select ‘Remove from Chrome’
On a Chromebook (that uses Chrome OS), you need to remove the YouTube extension.
Update: Google has fixed this issue in Chrome Canary 47, we’ll update this post with more information when the patch lands on Chrome 46 or 45.